Expression and glycosylation status of Na/Ca exchangers in normal and CDG patient platelets

ASTEGGIANO, CARLA; BISTUÉ MILLÓN, MB; SIRAVEGNA M; ELSO DE BERBERIAN G.

Rosario

Congreso; l Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Celular (SAIB); 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Celular (SAIB)

Congenital Disorders of Glycosylation (CDG) are genetic diseases due to defects in the synthesis of glycoconjugates. The clinical features are often neurological impairments and thrombus-hemorrhagic events. A tight regulation of Ca+2 is necessary to prevent inappropriate thrombus formation in platelet activation. The Na+/Ca2+ exchangers (NCX protein families) participate in Ca+2 cellular homeostasis. Recently, it has been described that human platelets expresses K+-independent (NCX1 and NCX3) and K+-dependent Na+/Ca+2 exchangers (NCKX1). In microsomal fractions of human platelets we assay the Na+-dependent 45Ca+2 uptake. The immunopurification of both proteins and Western blot were done using lectins (ConA and WGA) and NCX antibodies. Our first results indicated NCX1 is an N-glycoprotein and NCKX1 an O-glycoprotein. Additionally, two PMM2-CDG patients were detected. The P1 (p.R141H;p.E139K) and P2 (p.R141H;V231M) presented a severe phenotype and abnormal secondary platelet aggregation (P2). We found that the expression of NCX1 as well as the Na+-dependent 45Ca+2 uptake was greatly diminished in platelets from PMM2-CDG patient with abnormal platelet aggregation. We report for the first time, experimental data about the glycosylation status of Na+/Ca+2 platelet exchangers and a putative role of these proteins in the thrombus-hemorrhagic events associated to CDG.